I have noticed many times that internet users face problems while using Internet Download Manager because it is not a free software now. So, it first needs to be cracked which is a little irritating task. So, i have come up with a much better software to download Youtube or any other kind of .flv or .mp4 videos. And the software is One-Click Youtube Downloader.
You can download it here.
Download One-Click Youtube Downloader

For One-Click Youtube Downloader to work, you just need any downloader like Orbit Downloader which you can download from the following link

Download Orbit Downloader

One-Click Youtube Downloader gives you a floating Get-It button on your browser screen whenever a flash document is opened. Click on the drop-down arrow of Get-it button and select the video file to download or simply click on the Get-it button. You can check your file download progress by opening your downloader.